The present invention is generally related to water softeners, and, more particularly, to a controller and method for controlling regeneration of a water softener based on the total hardness (e.g., concentration of calcium carbonate) removed from the influent water to the softener. Here, total hardness is defined as the hardness of the water times the total volume of water softened.
Municipal water treatment plants often draw water from several sources that vary in hardness. For example, when the source of the water is groundwater, the water can be relatively hard, which is equivalent to, for example, a high concentration of calcium carbonate. However, when the source of the water is surface water, the water can be relatively soft, such as characterized by a low concentration of calcium carbonate. Many municipal water treatment plants use both types of water in varying proportions. The proportion of hard and soft water used by a municipal water treatment plant may also vary over time. Therefore, the hardness of the water actually delivered to the consumer can vary considerably throughout the year. Many consumers use water softeners to soften the water used in their homes, the work place, schools, etc. These water softeners are typically preset to soften water of a predefined degree of hardness. The presetting action assumes that the predefined hardness of the influent water to the softener remains constant.
Thus, in the past, it has been assumed that the hardness of the influent water to the water softener remained constant. Further, it is believed that the only variable that water softeners have been known to measure is the volume of water treated by the softener. Hence, if the water hardness varied, the softener would undesirably regenerate prematurely or not often enough.
In view of the foregoing considerations it would be desirable to provide a water softener and techniques that permit measuring the variability of the hardness of the water over time. It would be further desirable to provide a water softener with a regeneration controller programmed to regenerate the softener based on the total hardness removed from the influent water, as opposed to based on an assumption likely to incorrectly reflect the actual composition of the water. It would be further desirable to provide a regeneration technique that avoids any unnecessary discharge of salt (e.g., brine) to the surrounding environment.
Generally, the present invention fulfills the foregoing needs by providing in one aspect thereof, a regeneration controller for a water softener comprising a water meter configured to output a signal indicative of the volume of influent water received by the water softener. A water-hardness indicator, such as a conductivity meter or an ion-selective electrode, is configured to output a signal indicative of a degree of water hardness of the influent water, such as may be indicated by a conductivity measurement or a calcium concentration measurement, respectively. A processor is coupled to receive the respective signals from the water meter and the water-hardness indicator. The processor is further configured to calculate a value indicative of the total level of hardness removed by the water softener. A comparator is coupled to receive a signal indicative of the quantity of resin capacity of the water softener. The comparator is further configured to receive the value indicative of total hardness to issue a regeneration command based on comparing the resin capacity relative to the value of total hardness.
In another aspect thereof, the present invention further fulfills the foregoing needs by providing a method for controlling regeneration of a water softener. The method allows measuring the volume of influent water received by the water softener. The method further allows measuring a signal indicative of a degree of hardness of the influent water, such as by measuring the degree of conductivity of the influent water or the concentration of calcium in the water. A value indicative of the total quantity of hardness removed by the water softener is calculated. The resin capacity of the water softener is provided, e.g., is known. The resin capacity is related to the value of total hardness to determine whether or not regeneration is to be commanded for the water softener.